What is the difference between ser and estar?

Though both ser and estar are the Spanish infinitives of ‘to be’, they are used in different contexts. Ser is usually used for permanent states of being, whereas estar is used for temporary states. The acronyms DOCTOR and PLACE can be used to remember which situations require ser and which require estar.
DOCTOR stands for description, occupation, characteristic, time, origin and relationship. These are the instances where ser must be used. PLACE stands for position, location, action, condition and emotion, which are the instances where estar should be used.